Effect of female age on the diagnostic categories of infertility

As more women choose to delay childbearing, increasing numbers of them face age-related fertility problems. We aimed to explore the association between age and diagnosed causes of female infertility.

Anonymized data (age of male and female partner, year of first visit, diagnosis, duration and type of infertility) were obtained on all couples attending Aberdeen Fertility Centre from 1993-2006. The prevalence of different causes of infertility was determined for women <35 and >or=35 years of age at the time of their first clinic visit. Binary logistic regression and multinomial regression were used to determine the association between age and diagnostic categories of infertility.

Of a total of 7172 women, 26.9% were over the age of 35 years and 51.4% of the total had primary infertility. The mean female age was 31.2 (5.2 SD) years. There was an association between female age and the cause of female infertility (likelihood ratio, P < 0.001). More women over 35 had unexplained infertility (26.6 versus 21.0%, P < 0.001). Compared with women under 30 years, the adjusted odds ratio (95% confidence intervals, CI) of the following diagnoses in women over 35 were: unexplained infertility = 1.8 (1.4-2.2), ovulatory dysfunction = 0.3 (0.3-0.4) and tubal factor = 2.2 (1.7-2.7).

The causes of infertility in older women are different from those in younger women. Women over 35 years of age are nearly twice as likely to present with unexplained infertility.